MacOS webcam capture

[totaam]

A native port should solve #1113 on OSX (also blocked by #840) and will allow us to improve platform support and remove the dependency on opencv.

Also remove the hard-coded csc dependency.

[totaam]

Hopefully we can use the same code for enumerating video devices on osx. (see #1113#comment:4)

The same code can probably be used to capture the whole desktop on win32: DirectShow and may help with #389.

[totaam]

Alternatively, we may be able to the same thing using pyobjc:

• How to capture frames from Apple iSight using Python and PyObjC?
• How can I capture iSight frames with Python in Snow Leopard?

[totaam]

2018-02-01 14:36:26: antoine uploaded file webcam.py (3.5 KiB)

working capture script

[totaam]

The macos capture script above is based on How can I capture iSight frames with Python in Snow Leopard?. It works.. just not on my dev VM (light comes on, but frames never arrive), so I have to ssh to the mac mini to test it.

Still TODO:

• clean it up and add it to "darwin" webcam module
• implement device enumeration
• improve memory management so we can compress in another thread and release the buffer after we're done
• port to AVFoundation (ie: AVCaptureDevice) since all the documentation for QTKit is now 404 (dead links everywhere - thanks apple!): Transitioning QTKit Code to AV Foundation

Note: the py2app packaging for QTKit involved using packages and not modules? (IIRC)

---

For win32:

• Audio/Video Capture
• MFCaptureToFile Sample

See also #1627

[totaam]

2018-02-04 08:08:41: antoine uploaded file opencv.patch (3.6 KiB)

PKGBUILD patch to limit the number of opencv modules we build with makepkg

[totaam]

The patch above removes all the dependencies we don't need from the opencv MSYS2 package build, saving around 80MB of disk space.
The savings for our installer package are much smaller (~5MB) because we already trimmed it quite a bit and the file is compressed.

This should make things less brittle too: the opencv package seems to break very regularly in MSYS2 due to the huge amount of dependencies it has and because of the way the module loads them all - they would need to rebuild the package every time a dependency is updated.

Only problem is that the 32-bit version crashes hard, even the simple opencv_version.exe tool does... so r18290 disables webcam support in 32-bit builds.

[totaam]

2018-02-04 15:08:43: antoine uploaded file webcam_avfoundation.py (3.7 KiB)

port to AVFoundation

[totaam]

We now build AVFoundation (r18246, also for python3: r18296 + r18297), and we have a nasty py2app packaging workaround too: r18298.

The webcam port to AVFoundation above might work, but we're blocked by this pyobjc bug: Support marshalling OS_dispatch_queue on macOS 10.10 and 10.11
I'm not sure if this can be worked around using ctypes either.

Once that's fixed, we'll need to to parse the sampleBuffer object using:
from Quartz import CoreVideo then:

• CMSampleBufferGetImageBuffer
• CVPixelBufferLockBaseAddress
• CVPixelBufferGetBaseAddress
• CVPixelBufferGetWidth
• CVPixelBufferGetHeight
• CVPixelBufferGetBytesPerRow
• CVPixelBufferUnlockBaseAddress

[totaam]

pyobjc has moved to github: https://github.com/ronaldoussoren/pyobjc/
But this particular issue was not, it's been wiped like it never existed!